The subject matter disclosed herein relates to electrical circuit breakers, and more particularly, to circuit breaker control.
Generally, electrical circuit breakers include a trip coil responsive to over-current events. The trip coil may “trip” if an over-current event exists. Furthermore, the trip coil may be responsive to trip signals of a trip unit. The trip coil may therefore also trip to open the circuit breaker in response to a trip signal. The trip signal may be initiated within the circuit breaker or transmitted to the circuit breaker from a central controller. The electrical circuit breakers may also include a shunt trip coil. The shunt trip coil may be a mechanical or electrical-mechanical trip coil. The shunt trip coil may trip if a mechanical linkage or trip lever is activated. The shunt trip coil may also be responsive to shunt trip signals of a trip unit. Therefore, the shunt trip coils may also trip in response to a shunt trip signal. The shunt trip signal may be initiated within the circuit breaker or transmitted to the circuit breaker from a central controller.
If an over-current event exists, the trip unit of the circuit breaker may sense the over-current condition, and attempt to open contacts of the circuit breaker. In situations where a relatively large current is flowing across the contacts of the circuit breaker, a large force may be necessary to open said contacts. If the trip coil does not provide enough force, the contacts may remain closed, and may allow the over-current condition to damage any components within the circuit of the circuit breaker.
Shunt trip coils may provide a relatively larger force to open contacts of the circuit breaker. Shunt trip coils may be signal-tripped coils, over-voltage coils, under-voltage coils, and/or any combination thereof. However, as shunt trip coils provide a relatively larger force than trip coils, there may be more power required to energize the shunt trip coil. Thus if a large number of shunt trip coils are energized at substantially the same time, a relatively significant amount of current is drawn.
Therefore, in scenarios where a limited amount power is available or desirable, it may be beneficial to limit the number of shunt trip coils and trip coils energizing at substantially the same time. Furthermore, if predetermined conditions exist, for example large current flow conditions or other similar conditions, it may be beneficial to energize a shunt trip coil alongside a trip coil to increase the force applied to electrical contacts of a circuit breaker.
Thus, example embodiments provide methodologies of circuit breaker control taking into consideration any system power limitations in addition to coil operation.